Bulgarian Chemical Communications, Volume 50, Issue 4 (pp. 560 – 567) 2018

560

Instabilities during electrochemical deposition of Sn-Co alloys from

gluconate/sulphate electrolyte

T. T. Valkova*, I. N. Krastev

Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Received, September 15, 2017; Accepted, July 30, 2018

Dull coatings with high cobalt content can be deposited from the investigated electrolyte. Depending on tin

concentration, the deposition of coatings with cobalt content in the range from 0 up to 80 wt. % is possible.

Electrochemical instabilities and spontaneous potential oscillations during galvanostatic deposition of Sn-Co alloys are

observed and discussed.

Keywords: Electrodeposition, Tin-cobalt alloys, Oscillations

INTRODUCTION

Electrodeposited tin-cobalt alloy coatings are of

commercial interest as a convenient and economic

way to achieve an attractive finish [1, 2]. Bright tin-

cobalt alloy coatings have mechanical and

electrochemical properties similar to those of

chromium coatings and can be considered as their

effective substitution, especially where the high

corrosion resistance of chromium is not needed [3].

Tin-cobalt alloys [4] and compositionally

modulated Sn-Co multilayer alloy coatings [5] are

alternative to lead-based alloys used as overlays for

plain bearing.

Tin-based compounds have received particular

attention in the field of lithium batteries for the

synthesis of new negative electrode materials as

alternatives to graphite materials. Tin-cobalt alloy

found extensive application in this field [6-10],

because it has been shown that the addition of Co

gives the highest specific capacity [11], avoiding

mechanical stress due to the Li-intercalation

process [12].

According to the phase diagram Sn-Co alloy

may be composed of various intermetallic

compounds depending on its metal content [13].

The preparation of heterogeneous coatings offers

possibilities for investigation of the self-

organization phenomena as seen during the

deposition of other cobalt alloys – i.e. those with

indium and antimony [14].

The deposition of this alloy is performed from

sulphate/gluconate [15-17], citrate [18] and

pyrophosphate [19] electrolytes. All of them are

environmentally friendly, non-toxic, and non-

corrosive and electrodeposition process takes place

at high energy efficiency.

Electrochemical oscillations observed during

deposition of tin can be associated with both

electro-oxidation and electro-reduction process.

Cathodic potential oscillation of a Sn electrode

immersed in alkaline (KOH) solution of SnO has

been described by Piron et al. [20]. Oscillations

took place only at current densities higher than the

limiting current density and in a limited SnO

concentration range. The potential increase is due

to the depletion of tin ions near the electrode, and

the potential decrease results from hydrogen

evolution. Potential oscillations during deposition

of tin from acidic stannous sulphate solution

containing gelatine were investigated by cyclic

voltammetry and chronopotentiometry. In the

absence of gelatine damped potential oscillations

are evident (dendritic growth). In its presence

(gelatine acts as inhibitor and gives a smooth

deposit) substantial potential oscillations occur

[21].

Electrochemical oscillations during deposition

of tin alloys were first reported by Survila et al.

[22]. They found oscillations during the deposition

of Cu-Sn alloy from an acidic solution containing

Laprol 2402C. Later Nakanishi [23, 24] showed

formation of layered nanostructures during

electrodeposition of Cu and Sn in an acidic solution

in the presence of cationic surfactant. The

electrodeposition of the alloy is characterized by a

negative differential resistance (NDR) and resulting

current oscillations. Alloy films deposited during

the oscillations have multi-layered structure

composed of two alloy layers of different

compositions. The multilayers have the period of

thickness of 40-90 nm and were uniform over an

area of ca. 1×1 mm. NDR arises from adsorption of

a cationic surfactant on the alloy surface and the

© 2018 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria

* To whom all correspondence should be sent:

E-mail: krastev@ipc.bas.bg

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

561

oscillations occur from coupling of the NDR with

the ohmic drop in the electrolyte [24].

In another work the same authors investigated

the mechanism of oscillations and formation of

nano-scale layered structures during induced co-

deposition of some iron-group alloys (Ni-P, Ni-W

and Co-W) by an in situ electrochemical quartz

crystal microbalance technique [25]. They found

that the electrodeposition of these alloys is

connected with a negative differential resistance

(NDR), from which the oscillations and the layer-

structure formation arise.

Recently, Ihara et al. [26] showed that a large

interfacial energy gradient is produced at the front

of an electrochemical wave in Cu-Sn oscillatory

electrodeposition. They observed the directional

later motion of an oil droplet put on an electrode

surface. During the deposition, when oscillations

occur, surface composition changed periodically

between Cu-rich and Sn-rich alloy layers.

Many other electrochemical systems are known

to exhibit complex non-linear behaviour such as

spontaneous oscillations of current or potential.

Kaneko et al. [27] investigated potential

oscillations during the deposition of cadmium and

established that they result from the decrease in the

surface concentration of cadmium ions (almost to

zero) and as a result the potential shifts rapidly and

reaches deposition of hydrogen. The evolved

hydrogen improves the mass transport process by

kind of agitating the electrolyte. As a result, the

surface concentration of cadmium ions increases

and the potential decreases again.

The oscillatory electrodeposition of Sn and

some Sn containing alloys allows the assumption of

the possible appearance of some oscillating

electrochemical reactions also during deposition of

tin-cobalt alloys.

The aim of the present work is to investigate the

electrodeposition of a Sn–Co alloy from

gluconate/sulphate electrolytes and to find out the

conditions for the possible oscillating behaviour of

the system.

EXPERIMENTAL

The composition of the electrolyte for

deposition of Sn-Co alloy coatings is given in Table

1.

Table 1. Electrolyte composition

Composition Concentration, g dm-3

Sn as SnMS 0 - 15

Co as CoSO4.7H2O 0 - 15

Na2SO4. 0 - 50

C6H11O7Na 0 - 150

NaOH 0 - 5

Distilled water and pro analysi grade reagents

were used. The experiments were performed in a

glass cell of 100 cm-3 at room temperature without

stirring of the electrolyte. The working electrode (1

cm2) and the two counter electrodes were made of

platinum. A reference electrode Ag/AgCl with

EAg/AgCl = +0.197 V against the hydrogen electrode

was used. All potentials in the present study are

given against this reference electrode.

The cyclic voltammetric investigations were

performed by means of a computerized

potentiostat/galvanostat PAR 273A (Princeton

Applied Research) using the PowerCorr software

for electrochemical corrosion studies.

The sweep rate of the potential was 0.020 V s-1.

The alloy coatings, ca. 5 µm thick, were deposited

on 0.3 mm thick copper substrates, 2×1 cm, in an

electrolysis cell of 100 cm3. The cobalt content in

the coatings and their thickness was determined

using a Fischerscope XDAL apparatus for X-ray

fluorescence.

RESULTS AND DISCUSSION

Figure 1 shows the cyclic voltammetric curves

in electrolytes containing ions of both metals

separately and together. In this case, tin is the

nobler component (the deposition peaks of tin are

less cathodic (less negative) compared to the peak

of pure cobalt). During the deposition of tin two

cathodic reactions are observed again. The cobalt

deposition from the same electrolyte in the absence

of tin is characterized by one cathodic reaction.

When cobalt is added to the solution of tin two

cathodic maxima are observed again. The first one

is in the form of a hump and the second one is well

expressed. The first cathodic maximum

corresponds to the deposition of pure tin and the

second cathodic maximum to the co-deposition of

cobalt.

-1,0 -0,5 0,0 0,5-0,02

-0,01

0,00

0,01

0,02

j , A

/ c

m-2

E, mV

Fig. 1. CVA curves of tin, cobalt and SnCo alloy

deposition from sulphate/gluconate electrolytes at pH=5.

C Na2

SO4 = 40 g dm-3; C C

6H

11NaO

7 = 50 g dm-3; v = 20 mV

s-1; _____ CSn = 5 g dm-3;---- CCo = 5 g dm-3 ; …. CSn = 5 g

dm-3, CCo =5 g dm-3.

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

Two anodic reactions are detected in the case of

dissolution of tin and one during dissolution of

cobalt and the alloy. The main oxidation peak of

the alloy is in the potential range where dissolution

of tin and cobalt takes place.

Cobalt electrodeposition

0 200 400 600 800 1000 1200

-1,4

-1,2

-1,0

-0,8

-0,6

-0,4

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

b)

c)

Fig. 2. Chronopotentiometric curves obtained at

different current densities. CCo = 5 g dm-3; CSn = 0 g dm-3

(а) 0.2 А dm-2, (b) 0.4 А dm-2, (c) 1.4 А dm-2

Figure 2 shows the chronopotentiometric curves

obtained at different current densities at cobalt

concentration of 5 g dm-3 and pH=4. The increase

in the current densities leads to a small shift of the

cathodic potential without appearance of any

instabilities or oscillation reactions.

Tin electrodeposition

0 200 400 600 800 1000 1200

-2,4

-2,0

-1,6

-1,2

-0,8

-0,4

E(v

s A

g/A

gC

l) / V

Time/ s

a)

b)

c)

Fig. 3. Chronopotentiometric curves obtained at

different current densities at pH=3.5. CSn = 10 g dm-3;

CCo = 0 g dm-3. (а) 0.4 А dm-2 (b) 0.6 А dm-2 (c) 1.6 А

dm-2

Figure 3 shows the chronopotentiometric curves

obtained at different current densities at pH=3.5

and tin concentration of 10 g dm-3. Up to the

relatively high current density of 1.0 А dm-2 there

are no instabilities appearing (curves a, b). The

increase of the applied current density up to 1.6 А

562

dm-2 leads to the appearance of irregular, not so

well formed potential oscillations (curve c). They

have maximal amplitude of about 300 mV and their

period differs between 12 and 25 s. The oscillations

appear at this pH value at the high current densities

possibly due to the reduced passivation of the

electrode in the acidic media.

0 200 400 600 800 1000 1200

-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

VTime/ s

b)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

c)

Fig. 4a. Chronopotentiometric curves obtained at

different current densities at pH=5. CSn = 5 g dm-3; CCo =

0 g dm-3. (а) 0.4 А dm-2 (b) 0.6 А dm-2 (c) 0.8 А dm-2

Figure 4a shows the chronopotentiometric

curves obtained at different current densities at

increased pH value (pH=5) and a tin concentration

of 5 g dm-3. The increase of the pH of the

electrolyte leads to appearance of potential

oscillations at current densities between 0.4 А dm-2

and 1 А dm-2. The oscillations have amplitude of

about 600 mV. At current densities of 0.4 А dm-2

the period of the oscillations is about 15 s. At

higher current densities the oscillations start at the

beginning of the process with amplitude of about

500 mV, and after disappearing in a broad interval

of about 700 s they appear again irregular with

some higher amplitude of about 700 mV. At current

densities 0.6 А dm-2 the period of the oscillations is

about 25 s.

The influence of the concentration of tin in the

electrolyte is shown in Fig 4b. This figure presents

the chronopotentiometric curves obtained at a

higher tin concentration of 10 g dm-3 at different

current densities and pH=5. At current densities up

to 0.2 А dm-2 no oscillations are registered.

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

563

0 200 400 600 800 1000 1200

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000 1200

-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

b)

0 200 400 600 800 1000 1200

-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

c)

0 200 400 600 800 1000 1200

-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gCl)

/ V

Time/ s

d)

0 200 400 600 800 1000 1200

-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

e)

Fig. 4b. Chronopotentiometric curves obtained at

different current densities at pH=5. CSn = 10 g dm-3; CCo

= 0 g dm-3. (а) 0.2 А dm-2, (b) 0.4 А dm-2, (c) 0.6 А dm-2,

(d) 1.0 А dm-2, (e) 1.4 А dm-2

The increase in the applied current density up to

0.4 А dm-2 leads to the appearance of regular

potential oscillations with a high amplitude of about

700 mV, more regular than the oscillations obtained

at 5 g dm-3 Sn (compare with Fig 4a). The period of

the oscillations is about 12 s. At current densities of

1.0 А dm-2 the period of the oscillations differs

between 5 s at the beginning and 20 s at the end of

deposition. Similar results are observed at 15 g dm-3

Sn in the electrolyte. From the curves in Fig. 4b it

is visible, that the period of oscillations increases

with the time of deposition.

The effect of the concentration of the complex

forming agent for tin (C6H11O7Na in this case) on

the electrode processes is shown in Fig.5a.

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

a)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

b)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

c)

Fig. 5a. Chronopotentiometric curves obtained at

current densities of 0.2 А dm-2 at pH=5. CSn = 5 g dm-3;

CCo = 0 g dm-3. (а) CC6H

11O

7Na = 50 g dm-3, (b) CC

6H

11O

7Na

= 100 g dm-3, (c) CC6H

11O

7Na = 150 g dm-3

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

b)

0 200 400 600 800 1000 1200-2,0

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

c)

Fig. 5b. Chronopotentiometric curves obtained at

different current densities at pH=5. CSn = 10 g dm-3; CCo

= 0 g dm-3; CC6H

11O

7Na = 150 g dm-3. (а) 0.2 А dm-2, (b)

0.4 А dm-2, (c) 0.6 А dm-2

In a previous paper the function of the complex

forming agent on the electrodeposition of Sn and

SnCo alloy is described [28]. At low current

densities of about 0.2 А dm-2 and 50 g dm-3 of

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

564

C6H11O7Na some small oscillations appear in a

short period of the deposition (curve a). The

increase of the concentration of gluconate up to 100

g dm-3 leads to the appearance of potential

oscillations with a high amplitude of about 800 mV

and a period of about 44 s (curve b). Similar results

are obtained with 150 g dm-3 C6H11O7Na in the

electrolyte, but with a smaller period of the

oscillations about 28 s (curve c).

At a higher concentration of C6H11O7Na (100-

150 g dm-3) oscillations appear only at low current

densities of about 0.2 А dm-2. The increase of the

current density results in the disappearing of the

oscillations (Fig.5b).

Tin-cobalt electrodeposition

0 200 400 600 800 1000

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

b)

0 200 400 600 800 1000

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

c)

0 200 400 600 800 1000

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

d)

Fig. 6. Chronopotentiometric curves obtained at

different current densities at pH=3.5. CSn = 5 g dm-3; CCo

= 5g dm-3. а) 0.8 А dm-2, (b) 1.0 А dm-2, (c) 1.6 А dm-2,

(d) 2.0 А dm-2

Figure 6 shows chronopotentiometric curves

obtained at different current densities at pH=3.5

and tin concentration of 5 g dm-3 and cobalt

concentration of 5 g dm-3. At low current densities

up to 1.0 А dm-2 there are no oscillations registered

(curves a, b). The increase of the applied current

density up to 1.6 А dm-2 leads to the appearance of

potential oscillations with an amplitude of about

200 mV. The period of the oscillations is about 20 s

and they disappear after a deposition time of about

400 s. The further increase in the current density up

to 2.0 А dm-2 leads to the appearance of potential

oscillations with similar amplitude, but with a

shorter period of about 9 s.

0 200 400 600 800 1000 1200

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000 1200

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

b)

0 200 400 600 800 1000 1200

-1,6

-1,2

-0,8

-0,4

0,0

E(vs

Ag/

AgC

l) / V

Time/ s

c)

0 200 400 600 800 1000 1200

-1,6

-1,2

-0,8

-0,4

0,0

E(vs

Ag/

AgC

l) / V

Time/ s

d)

0 200 400 600 800 1000 1200-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) / V

Time/ s

e)

Fig. 7. Chronopotentiometric curves obtained at

different current densities at pH=5. CSn = 5 g dm-3; CCo =

5g dm-3. а) 0.6 А dm-2, (b) 0.8 А dm-2, (c) 1.0 А dm-2, (d)

1.4 А dm-2, (e) 2.0 А dm-2

Figure 7 shows the chronopotentiometric curves

obtained at different current densities at an

increased pH value (pH=5), and the same

concentrations of both metals in the electrolyte. In

this case at current densities up to 0.6 А dm-2 no

oscillations are observed (curve a). The appearance

of potential oscillations starts at lower current

densities compared to the more acidic electrolyte.

At current densities 0.8 А dm-2 stable potential

oscillations with amplitude of about 300 mV are

registered. The period of the oscillations decreases

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

565

from about 26 s at 0.8 А dm-2 to about 10 s at 2.0 А

dm-2.

In order to find out the differences during

deposition at а positive potential of the oscillations

and at а negative one, two samples were deposited

potentiostatically in the investigated alloy

electrolyte at the potentials of -1.2 V and -1.5 V

(the most positive and the most negative potentials

in the oscillation curve (Fig.7 (curve b), current

density 0.8 А dm-2) for 300 s.

a)

b) Fig. 8. Surface of tin-cobalt alloy coatings. CSn = 5 g

dm-3; CCo = 5g dm-3; pH=5. a) -1.2 V; 60 wt. % Co, b) -

1.5 V; 50 wt. % Co

The appearance of the obtained coatings was

different - the coating deposited at -1.2 V was

silvery white while that, deposited at -1.5 V was

dark-grey. The morphology of these coatings is

shown in Fig. 8. The deposit obtained at -1.2 V

contains about 60 wt. % of Co and the deposit

obtained at -1.5 V about 50 wt. % of Co. The

coatings obtained at the higher potentials are

course-grained and rough and possibly that is the

reason for the lower cobalt content.

Figure 9 shows the chronopotentiometric curves

obtained at different current densities at pH=5 and

higher tin concentration of 10 g dm-3 with a cobalt

concentration of 5 g dm-3. At current densities up to

0.8 А dm-2 no oscillations are registered (curve a)

and the obtained coatings are bright. The increase

in the applied current up to 1.0 А dm-2 leads to the

appearance of potential oscillations with an

amplitude of about 200 mV. The period of the

oscillations is about 20 s. The increase in the

current densities up to 1.4 А dm-2 leads to the

formation of oscillations with a larger amplitude of

about 300 mV and a shorter period of 12 s.

0 200 400 600 800 1000

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

a)

0 200 400 600 800 1000

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

b)

0 200 400 600 800 1000

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

c)

0 200 400 600 800 1000

-1,6

-1,2

-0,8

-0,4

0,0

E(v

s A

g/A

gC

l) /

V

Time/ s

d)

Fig. 9. Chronopotentiometric curves obtained at

different current densities at pH=5. CSn = 10 g dm-3; CCo

= 5g dm-3. (а) 0.6 А dm-2, (b) 1.0 А dm-2, (c) 1.2 А dm-2,

(d) 1.4 А dm-2

Fig. 10. Effect of the current density on the cobalt

content in the alloy at different metal concentrations in

the electrolyte. ● CSn = 5 g dm-3; CCo = 5 g dm-3; CSn =

10 g dm-3; CCo = 5 g dm-3; ■ CSn = 5 g dm-3; CCo = 10 g

dm-3

T. T. Valkova and I. N. Krastev: Instabilities during electrochemical deposition of Sn-Co alloys from …

566

Figure 10 shows the effect of both tin

concentration and cobalt concentration in an

electrolyte at pH=5 on the composition of the alloy.

At 5 g dm-3 of Sn and 5 g dm-3 of Co in the

electrolyte the increase of the current density leads

to an increase of the cobalt content in the coating

up to 50 wt.%. At higher tin concentration of 10 g

dm-3 in the electrolyte, pure tin coatings are

deposited at low current densities and the cobalt

content in the coatings increases up to about 40

wt.%. In both cases the deposition of coatings with

almost constant composition is possible in a broad

range of current densities. In this case oscillations

of the cathodic potential are observed.

As expected, higher cobalt concentrations in the

same electrolyte result in the rise of cobalt content

in the alloy. At a cobalt concentration of 10 g dm-3

in the electrolyte, the cobalt content in the coatings

is higher and reaches 80 wt.%.

CONCLUSIONS

1. Potential oscillations with different

amplitude and period are registered during

electrochemical deposition of Sn and Sn-Co alloys.

2. At lower pH values of the electrolyte the

oscillations start at higher current densities during

deposition of Sn and Sn-Co alloys due to the

reduced passivation of the coatings in the more

acidic electrolyte.

3. The period of the oscillations increases with

the deposition time possibly due to the increase of

the roughness of the coatings and decreases with

the increase in the applied current densities.

4. The increase in Sn concentration in the

electrolyte results in more regular potential

oscillations.

5. The increase in the concentration of

complexing agent (gluconate) leads to disappearing

of the potential oscillations at high current

densities.

6. The instabilities and the resulting potential

oscillations during deposition of Sn-Co alloys are

due to the Sn-component of the electrochemical

system.

7. The observed potential oscillations during

galvanostatic electrodeposition of Sn-Co alloys

from gluconate/sulphate electrolytes are connected

with some passivation phenomena of the cathode

surface and the resulting hydrogen evolution.

Acknowledgements: The authors express their

gratitude to the National Science Foundation for

the financial support of the project T 02/27- 2014.

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НЕСТАБИЛНОСТИ ПРИ ЕЛЕКТРОХИМИЧНОТО ОТЛАГАНЕ НА Sn-Co СПЛАВИ ИЗ

ГЛЮКОНАТНО-СУЛФАТЕН ЕЛЕКТРОЛИТ

T. T. Вълкова*, И. Н. Kръстев

Институт по физикохимия, Българска академия на науките, 1113 София, България

Постъпила на 15 септември, 2017, приета на 30 юли 2018

(Резюме)

Матови покрития с високо съдържание на кобалт могат да се отложат из изследвания електролит. В

зависимост от концентрацията на калай е възможно отлагане на покрития със съдържание на кобалт от 0 до 80

wt. %. При галваностатичното отлагане на Sn-Co сплави са наблюдавани и дискутирани електрохимични

нестабилности.